Rescuing a Quantum Phase Transition with Quantum Noise

TL;DR

This paper demonstrates that quantum noise from an environment can actually restore and enhance quantum phase transitions in a double quantum dot system, contrary to typical destructive effects.

Contribution

It reveals that quantum noise can rescue a quantum phase transition and identifies a non-Fermi-liquid fixed point influenced by environmental noise.

Findings

Quantum noise reduces charge transport in the system.

Restoration of the quantum phase transition by environmental coupling.

Identification of a non-Fermi-liquid fixed point similar to the two-impurity Kondo model.

Abstract

We show that placing a quantum system in contact with an environment can enhance non-Fermi-liquid correlations, rather than destroy quantum effects as is typical. The system consists of two quantum dots in series with two leads; the highly resistive leads couple charge flow through the dots to the electromagnetic environment, the source of quantum noise. While the charge transport inhibits a quantum phase transition, the quantum noise reduces charge transport and restores the transition. We find a non-Fermi-liquid intermediate fixed point for all strengths of the noise. For strong noise, it is similar to the intermediate fixed point of the two-impurity Kondo model.